Regulation Of The Bacterial Biofilms Adhesion And The Quantification Of The Adhesion Force

Biofilm is one of the most important substance in nature, which plays an irreplaceable role in the survival and development of microorganisms. As the isomer of amino acids, D-amino acids could inhibit bacterial biofilm formation and mature biofilm disassembly; however, the mechanisms were unclear yet.This research was amined at the effect of D-amino acids on the transport of Escherichia coli MG1655 within porous media. The cells were cultivated from the LB media containing different concentrations of D-tyr. The experiments conducted on the bacterial its transfer characteristics in porous quartz sand column, physicochemical properties, and the extended DLVO (XDLVO) theory was used to analyze the thermodynamics mechanism. Meanwhile, a conwection diffusion model was used to Simulate and analysze of the migration and deposition behavior of bacteria. The results show that under the influence of D-Tyr, breakthrough curves of bacterial transport in the porous media have increased significantly, in quartz sand, the deposit of the bacterial number decreased with increase of D-Tyr concentration.In order to further explore the formation mechanism of bacterial biofilm, this study selects the typical metal reducing bacteria Shewanella oneidensis MR-1 to explore the role of outer membrane proteins in the process of bacterial biofilm formation. After knockout the gene of the three outer membrane porteins, the formation of the biofilem, the surface properties were determined. At the same time, the adhesion of the mutant on the ITO with or without Fe2O3 also were experimented on. For further study of bacterial adhesion and aggregation, atomic force microscopy (AFM) is used in this experiment, through the determination of the interaction between the probe and the substrate and study of bacterial adhesion. The results showed that the biofilm formation was significantly blocked by the outer membrane protein gene knockout, and the adhesion and aggregation of the bacteria were lower than that of the wild strain.